The Big Thicket is the name given to a somewhat imprecise region of a heavily forested area of Southeast Texas in the United States. This area represents a portion of the mixed pine-hardwood forests or "Piney Woods" of the Southeast US. The National Park Service established the Big Thicket National Preserve (BTNP) within the region in 1974 and it is recognized as a biosphere reserve by UNESCO. Although the diversity of animals in the area is high for a temperate zone with over 500 vertebrates, it is the complex mosaic of ecosystems and plant diversity that is particularly remarkable. Biologists have identified at least eight, and up to eleven, ecosystems in the Big Thicket area. More than 160 species of trees and shrubs, 800 herbs and vines, and 340 types of grasses are known to occur in the Big Thicket, and estimates as high as over 1000 flowering plant species and 200 trees and shrubs have been made, plus ferns, carnivorous plants, and more. The Big Thicket has historically been the most dense forest region in Texas.
Existing literature states that Native Americans were known to have lived and hunted in the area nomadically, but did not establish permanent settlements there before the Alabama–Coushatta settled in the northeast about 1780. Spanish explorers and missionaries had a sporadic presence in the region, however colonization and settlement was not their aim, preferring to establish forts outside of the Region where the French were encroaching from the east (namely around Natchitoches, Nacogdoches, and the lower Trinity river valley). Logging in the late 19th and 20th centuries dramatically reduced the forest concentration. Efforts to save the Big Thicket from the devastation of oil and lumber industries started as early as the 1920s with the founding of the East Texas Big Thicket Association by Richard Elmer Jackson.
Conservatively the area occupies all of Hardin County, most of Polk, and Tyler Counties, and parts of Jasper, Liberty and San Jacinto Counties, including areas between the Neches River on the east, the Trinity River on the west, Pine Island Bayou on the south, to the higher elevations and older Eocene geological formations to the north. Broader interpretations have included the area between the Sabine River on the east and the San Jacinto River on the west including much of Montgomery, Newton, Trinity, and Walker Counties, as well. Several attempts to define the boundaries of the Big Thicket have been made, including a biological survey in 1936 which included over covering 14 counties. A later botanical based study in 1972 included a region of over . This same habitat extends into Louisiana and eastward.
Geography
Physical geography
[[File:Geological formations (diagonal center) of the Big Thicket Basin and the Epochs in which they were formed (lower right). This is a generalized illustration and it is not accurate in scale or proportion.jpg|thumb|Geological formations (diagonal center) of the Big Thicket Basin and the epochs in which they were formed (lower right). while others say it was the weight of the successive deposits that eventually caused the Gulf of Mexico to subside.
Soils: The soils of the various formations at the surface have shifted and intermingled through erosion and other factors over time and can be locally quite complex. The Big Thicket contains a greater variety of soils than any area of comparable size in the United States. Sources vary, but from 50 to 100 soil types are said to occur in Hardin County alone.
Hydrology: Hardin, Tyler, western Jasper and southeast Polk counties are drained by the Neches River and its tributaries: Village Creek and its smaller tributaries (Beach, Theuvenins, Turkey, Hickory, Kimball, Big Sandy, and Cypress creeks) in the north; Pine Island Bayou and its smaller tributaries (Little Pine Island Bayou and Mayhaw Bayou) in the south. Eastern regions, including eastern Jasper and Newton counties, are drained by several relatively short creeks running into the Sabine River. Western regions including central Liberty, northeastern San Jacinto, northern Walker counties and southwest Polk County (via Kickapoo, Long King, and Menard creeks) are drained by the Trinity River. Areas farther west are drained by the San Jacinto River, with east and west forks. Additional wetlands are extensive, including innumerable nameless swamps, cypress sloughs, oxbow lakes, wetland savannas, and baygall bogs. Floodplains and bottomlands in the south, can retain surface water for days and weeks after rain. The Sabine and Neches rivers flow into Sabine Lake, a natural occurring brackish water estuary, just southeast of the Big Thicket. The other large lakes in the region were constructed in the decades following the Second World War, including B.A. Steinhagen Lake (1947–53) and Sam Rayburn Reservoir (1956–65) on the Neches River drainage, Lake Livingston (1966–69) on the Trinity River, Lake Houston (1953) and Lake Conroe (1970–73) on the San Jacinto River. with northern areas receiving about , and southern areas receiving about . However, tropical storms and hurricanes can increase annual rainfall to over . Humidity stays well above 60% most of the time and exceeds 90% often. Winters are mild, with nighttime lows averaging and daytime highs . Winter cold fronts can drop temperatures to freezing, but freezes rarely last for more than a few days, sometimes only hours, averaging about 20 mostly nonconsecutive days each year. Snow is rare, occurring only once every ten years or so. Summer temperatures are hot, with nighttime lows averaging and daytime highs averaging . Temperatures exceed about 110 days each year and days with temperatures above and even above are not uncommon. The high summer temperatures with high humidity levels can produce very high heat index numbers.
Human geography
Population: In 2010, the United States Census Bureau reported a population of 54,635 for Hardin County, with an average of in a county of . The larger towns (and populations from 2010 census) in Hardin County are Kountze, the county seat (2,123), Lumberton (12,448), Silsbee (6,611), and Sour Lake (1,813). Smaller unincorporated communities in the Hardin County include Batson, Honey Island, Saratoga, Thicket, Village Mills, and Votaw.
Tyler County had a total population of 21,766, with an average population of in . The larger towns in Tyler County are Chester (312), Colmesneil (596), Warren (757), and Woodville, the county seat (2,586) with smaller unincorporated communities including Doucette, Fred, Rockland, and Spurger.
Polk County had a total population of 45,413, with an average of in an area of in 2010 including Livingston (5,335), the county seat and the largest town in the county.